Conventional light bars or task lights have an elongated housing containing a light source such as a fluorescent tube. The back of the light bar has mounting hardware for installation to an overhanging cabinet or overarching surface above the work area to be illuminated. Power for the light bar is supplied by a 120V/220V AC cable of a fixed, factory set length, usually 12 or 24 inches, extending out from one end of the housing. The AC cable terminates with a three-prong plug that inserts into a standard AC outlet.
There are task and undercabinet LED light bars commonly used to illuminate computer workstations. This category of light bars uses low voltage usually 12V or 24 VDC. The power source from the wall outlet is fed through a transformer including an AC-to-DC rectifier “brick” that has a cable terminating with a mini plug. The mini plug inserts into one end of the light bar. The cable is a preset length as decided by the factory, usually in 4-, 6-, or 12-foot precut sections. The cable may include an on/off power switch, or the power switch may be located on the light bar.